Airgun tune

[Nobade]

Anybody here ever try to do much to spring guns? Last night I finished a makeover of my Beeman R9 and was just astounded at the difference. I put delrin buttons on the piston, used a Maccari spring and seal, honed the chamber, made a shrouded barrel for it, delrin pivots for the cocking pivot, new crosspin with snap rings for the cocking arm, oil finish on the stock, etc. I couldn't believe the change! Instead of a "twang" and vibration it fires and stops. Much nicer and should be easier to shoot accurately.

I know there is an airgun forum here, but those guys never talk about working on them. This one is my first, and it was a lot of fun playing with something other than a powder burner for a change. Seeing how easy it is to make a dramatic improvement in them it seems like something a well equipped home 'smith might like to tackle. 

[IOWA DON]

My 124 FWB is nearly 30 years old and last summer I sent it away to have the seal, plunger and spring replaced. I think it was Maccari parts. The velocity was supposed to increase from 800 to 900 fps but I think it only got up to 830 fps or so. I chronographed it but forgot the exact number. However, the guy who replaced the parts said that the new parts would fit better and there would be less vibration. It seems to vibrate less and is much easier to hit and kill pest birds, rabbits and squirrels. That is, it now seems that how the rifle is held has much less effect on point of impact. Before, a solid hold would make the point of impact hit higher than a soft hold. Now there seems to be almost no difference. Before the rebuild it seems that squirrels were not consistently killed, but now its seems easy to get the pellet in exactly the right place and of the dozen or so I've shot at since the rebuild, all died quickly. Pest birds have small vital areas and it seems that more of them drop right away. Previously many flew off and died in my neighbors yards. They did not care, but I prefer they don't get that far.

[rzwieg]

I'd like to hear about how you did it.

[victorcharlie]

I looked at having Charlie the Tuna do a Tune on my Tech Force 99 but I just can't see spending the price of the gun on a tune.

http://charliedatuna.com/

I've heard he does a great job.

I have worked on the trigger a bit......

[STUMPJMPR]

I tuned a QB78 one time.  It was a C02 air rifle but i got decent performance out of it after the tune.  I could drop squirrels out the top of fairly tall pines without much trouble.

[handirifle]

Is there a source somewhere to see a cut away or some pics of CO2 guns?  I've often thought of making one, but not sure how the air charge is regulated.

Where'd you get the parts for the tune?

[STUMPJMPR]

http://www.gatewaytoairguns.com/library/Charlie%E2%80%99s%20QB-78%20Tune.htm
You can check out this site. QB78 is a good CO2 air rifle to tune and they are cheap.  They have a following kinda like you guys and the handi's...
The charge is regulated by a valvebody/stem.  It is similiar setup to the valve stem on a car tire....It has a springloaded hammer that strikes the valve stem and releases a small charge of gas which you know the rest.....  CO2 cooks off from a liquid to a gas to maintain around 800psi(about)...Thats what makes it a good gas, its fairly stable....